The vast majority of marks (errors) in those hot-metal days were the fault of the Teletypesetter system. A story would be keyboarded in Manchester and transmitted to London as a teleprinter spool; it was then fed on to an adapted typesetting machine. This may have saved money, but it resulted in a horrendous number of misprints that had to be corrected. As the London typesetters were not responsible for these marks, a small charge was negotiated. Newspapers were set at piecework rates in those days, in common with all other titles.

Source: The Guardian May 17, 2021 15:45 UTC